For the transport of moisture-sensitive goods, such as lime, the railways introduced so-called 'Lidded Freight Cars' in various designs from a very early stage. In the second half of the 1920s, the development of this car type resulted in the K Elberfeld 80 001 ff., which met the requirements for the 'Austauschbauart' (a design based on standardised components) that were valid at that time, and was standardised accordingly. The freight car had a length of 8.1 m (without handbrake) and 8.8 m (with handbrake), as well as the short 4 m wheel base that was typical for this period and had a maximum load of 17.5 t. In order to withstand this weight, the side panels and hinge lid were strengthened with prominent crossed beads. While the original paint was RAL 8012, with the undercarriage and offset fittings in RAL 9005, this quickly changed to light grey streaks when loaded with lime. The 991 freigt cars delivered by 1933 were also the last cars to be built in series. Although the lidded freight cars could be loaded mechanically, they could only be unloaded manually. As a result, the development of selfunloading cars for the transport of similar goods was already underway in the days of the Reichsbahn, and there were no significant new developments after the K25. Nevertheless, the vehicles classified by the Bundesbahn (Federal Railway) as K25 remained in regular service until the end of the 1960s and, in isolated cases, for even longer as service vehicles.
